Recently, the nano-imprinting techniques are attracting attention in various fields in order to further increase the density and accuracy.
For example, applications to semiconductors, optical elements, magnetic recording media, and the like are being examined.
A discrete track medium is attracting attention among other magnetic recording media. In this discrete track medium, magnetic interference between adjacent recording tracks is reduced by separating the adjacent tracks by grooves or guard bands consisting of a nonmagnetic material, in order to further increase the density.
When manufacturing this discrete track medium, discrete track patterns of a magnetic layer can be formed by applying the nano-imprinting technique by using a stamper. When magnetic layer patterns corresponding to servo area signals are formed together with recording track patterns by imprinting, it is possible to obviate the servo track writing step required in the manufacture of the conventional magnetic recording media. This leads to a cost reduction as well.
As the process of forming discrete track patterns as described above, it is possible to use, e.g., a manufacturing process of transferring resist patterns from an Ni stamper by high-pressure imprinting or thermal imprinting as disclosed in, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2007-186570. Unfortunately, this process is unsuitable for mass-production because the life of the Ni stamper is short. Also, when the data density is increased to make tracks finer, resist patterns cannot be well transferred.
From the foregoing, the use of optical nano-imprinting is attracting attention as another nano-imprinting technique.
To transfer patterns onto a resist on a discrete track medium by using optical nano-imprinting, a resin stamper is first duplicated from an Ni stamper (mother stamper) by injection molding, and bonded in a vacuum to an uncured ultraviolet-curable resin layer to be used as a resist. This method is found to be able to reduce the cost and suitable for micropatterning.
The characteristics required of the ultraviolet-curable resin for transfer onto the above-mentioned discrete track medium are the resistance against etching for processing transferred patterns, in addition to the property of coating onto the medium, the viscosity, the curing property, the property of separation from the resin stamper, and the cure shrinkage.